For example, a 4 WD (Four Wheel Drive) vehicle and an FR (Front engine Rear drive) vehicle use a saddle type fuel tank whose bottom side is curved upward at a center portion in the widthwise direction of the vehicle in order to avoid interference with a propeller shaft running through the center of the vehicle. Such a fuel tank adjoins the propeller shaft in the widthwise direction of the vehicle.
As shown in FIG. 6A, a differential gear 204 disposed rearward of a fuel tank 202 (in the direction of an arrow Rr) is coupled to the rear end of such a propeller shaft 200. A housing 206 accommodating the differential gear 204 is inserted into a through hole 210 formed in a rear sub-frame 208 forming a part of the vehicle body.
The housing 206 is mounted on the rear sub-frame 208 by a pair of mount parts 212L, 212R provided on both sides of a front end portion of the housing 206 in the widthwise direction of the vehicle (in the direction of an arrow L and direction of an arrow R) and a mount part 214 provided on the rear end of the housing 206 (see, for example, Japanese Unexamined Patent Application Publication No. 2000-43594).
The mount part 214 according to the related art includes a first bracket 216 connected to the housing 206, a second bracket 218 connected to the rear sub-frame 208, a bolt 220 that penetrates the first bracket 216 in the widthwise direction of the vehicle to fasten the first bracket 216 and the second bracket 218 together.
According to the foregoing related art, when a collision occurs on the front side of the vehicle, for example, the buffer load that acts rearward of the vehicle (toward the differential gear 204) is applied to the propeller shaft 200, so that the propeller shaft 200 may be broken and the connecting portion at which the propeller shaft 200 and the pair of mount parts 212L, 212R are connected may be fractured as shown in FIG. 6B.
As a result, moment in the direction of an arrow A acts on the housing 206, so that the portions at which the first bracket 216 and the second bracket 218 are fastened are separated from each other. Particularly, as apparent from FIG. 6B, force in the direction of pulling the bolt 220 acts on the housing 206, so that the bolt 220 is very likely to come off.
Consequently, as shown in FIG. 6C, the housing 206 separated from the rear sub-frame 208 may be thrown out forward of the vehicle (in the direction of an arrow Fr), and may collide with the fuel tank 202, thus damaging the fuel tank 202. The damage on the fuel tank 202 by the housing 206 separated from the rear sub-frame 208 this way may occur upon collision of the vehicle on its side, on its rear side or the like.
In addition, according to the related art, the separated housing 206 (differential gear 204) may hit a pedestrian, another vehicle or the like nearby.